1. Field of the Invention
The invention relates to a terminal fitting.
2. Description of the Related Art
Japanese Unexamined Patent Publication No. 2004-220964 discloses a terminal fitting formed by bending a metal plate material that has been punched out into a specified shape. The terminal fitting includes a rectangular tube and a resilient contact piece is accommodated in the rectangular tube. A male tab inserted into the rectangular tube is squeezed resiliently between a receiving plate of the rectangular tube and the resilient contact piece to achieve electrically conductive contact.
The resilient contact piece is hammered to form a contact portion with a small contact area for contacting the male tab. A resilient contact piece without a small contact portion is thought to define a wide contact area and a small electrical contact resistance. However, metal surfaces are rough when seen microscopically. Thus, the metals are in contact at a multitude of points in a low contact pressure state. These contact points have a high possibility of being separated if the resilient contact piece and the male tab displace slightly. Therefore, such a contact mode is unstable and there cannot be a high expectation for a reduction of contact resistance.
In contrast, contact pressure per unit area increases if an apparent contact area is made smaller by forming the contact portion. Therefore, the metal surfaces are deformed to conform to each other, and the area of the surface contact increases when seen microscopically. The contact state is maintained in the surface contact area even if the resilient contact piece and the male tab are displaced slightly from each other. As a result, a contact state in a wide area is maintained stably and contact resistance is reduced.
The contact portion of the above-described known terminal fitting is formed by hammering a part of the resilient contact piece to project from the surface of the resilient contact piece. Thus, the terminal fitting becomes bulkier by a projecting distance of the contact portion in a direction in which the male tab is squeezed between the resilient contact piece and the receiving plate.
The invention was developed in view of the above situation and an object thereof is to reduce the height of a terminal fitting.